Reloader and magnetic brake for automatic machine gun



l'()frt- 23', 1956 A. HARDY y 'RELOADER ANnfMAgNETIc BRAKE FOR AUTOMATIC1MM-:mmaY GUN Filed Feb'. 1.4. 1952 2 E Shee tS-Shet 2 with facility andspeed.

United States Patent() RELOADER AND MAGNETIC BRAKE Fok AUTOMATIC MACHINEGUN l Albert L. Hardy,

United States of tary of the Army Schenectady, N. Y., assignor to theAmerica as represented by the Secre- The present invention relates to anelectric charger and to a magnetic brake for the operating motor of anelectric charger or reloader for a machine gun.

Generally, guns of the type which are provided with an electric reloaderare recoil operated so that when the gun is tired, recoil of the barrelunlocks the breech and drives back the bolt. In moving back, the boltejects a spent cartridge, withdraws the firing pin, actuates the beltfeed mechanism to pull a cartridge toward the center of the beltfeedway, and cocks the bolt mechanism so that the next round can befired. Throughout recoil of the bolt a drivespring is being compressed,and if the sear has been depressed to free the bolt mechanism forcounter` recoil, either mechanically or electrically, the .bolt assemblyrebounds from the buifer mechanism and commences another firing cycle,and in so doing strips the live cartridge from its link in position onthe belt feedway and chambers it. The final forward movement of the boltpushes the tiring pin into and tire the cartridge.

Machine guns of the before-mentioned type haveused manual means forreloading and charging, when a new ammunition belt has been fed into thegun, or when a defective shell or dud has entered the chamber to destroythe recoil actuation of the gun. However, mechanical actuation has beenfound wanting in several important particulars; namely time and effortrequired to overcome the strength of the drive spring, and moreimportant, inaccessibility of the charger as, for example, in

. guns mounted in'the wings of airplanes.

Remotely controlled electric chargers, to replace the mechanical means,accomplish charging and reloading The charger is mounted within the beltfeed tube of a gun and is retained in place by means engaging a hole inthe cover of the gun. The charger motor is a high speed, series woundmotor with a double eld winding for rotating the armature in eitherclockwise or counterclockwise direction.4 The shaft of the motor isprovided with a driving connection to a lead screw which in turn isconnected to the bolt and to the feed tube, and the circuit whichincludes the fields of the motor is arranged so that closing of theloading switch energizes the power stroke field to rotate the motor andlead screw in a clockwise direction to withdraw the bolt to cock thegun, and to actuate the belt feedway by means of a rack connection withthe feed tube to commence the placement of a live cartridge in thechamber. As the bolt approaches full recoil position the bolt rides downa tell-tale which is connected to a tell-tale switch in the motorcircuit to de-energize the power stroke field and to energize the returnstroke eld to rotate the motor in counterclockwise direction. Theswitching to counterclockwise rotation from clockwise rotation, or viceversa, from clockwise to counterclockwise rotation if the need arises,should be effected instantaneously to prevent malfunctioning of thecharger. Functioning tests of machine guns supplied with electriccharges have disclosed failuresA of theA electric charger assembliesaggravated by position to strike the primer rice transmitting forcesresulting from motor armature inertia to the armature shaft andassociated motor springs and parts. Additinally, the tendency of thecharger mo'tor to overrun and to force the lead screw drive assemblyagainst the motor armature shaft has caused failures at weak points ofthe lead screw and at the motor housing bearing supports.

it is accordingly an object of this invention to provide means combinedwith the electric charger to dissipate armature energy of the reversingmotor more positively and to prevent excess forces from beingtransmitted to the lead screw and to motor components.

it is also an object of this invention to provide a magnetic brakehaving a solenoid coil in series with the power stroke and return strokefields of the charger motor, constructed and arranged to providepositive and immediate stopping of the armature when the motor isreversed.

lt is a further object of this invention to provide a magnetic brake forthe reversing motor of the charger mechanically arranged to allow theuse of an air gap which may be as little as .005 in the non-energizedposition with a resulting high pull for the brake size.

It is also a further object of this invention to provide a magneticbrake having a solenoid coil of heavy, low resistance wire arranged inseries with the power stroke field and return stroke eldv of the chargermotor to permit rapid braking action, with minimum delay by back E. M.F. current, due to residual field in the motor during stopping. i

With these and other objects in view, which will become apparent as thefollowing specification develops, reference is made to the accompanyingdrawing forming a part of the specification and wherein:

Figure 1 is vertical longitudinal section with some parts in elevationof an electric charger and pertinent parts, providedwith the magneticbrake of this invention, and mounted in the cover and receiver of themachine gun.

' Figure 2 `is an enlarged vertical longitudinal section of Y the rearportion of the electric charger and mechanical brake.

Y Figure V2a isa continuation of the section of Figure 2.

Figure 3 is a horizontal longitudinal section with follower in plan ofthe forward portion of the charger.

Figure 4 is an isometric view of the feed tube including the helicalgroove.

Figure S is a View of a disc which rotates with the motor shaft andwhich cooperates with the magnetic brake.

Figure 6 is a schematic diagram of the loading and power circuits to thecharger motor and brake, and the firing circuit'.

Referring to the drawing wherein are illustrated those parts of the gunwhich are most pertinent to the operation of the electric charger, andwhich are important from the standpoint of following through a typicalloading cycle, reference character 1 represents the receiver of amachine gun, and 2 is a cover for inclosing the top of the receiver. Thefront end of cover 2 is attached to the receiver by a hinge pin 3 whichengages a-hooked projection 4 on top of the receiver. Means (not shown)are also pivoted to latch the cover in place and maintain it closed.

A belt feed tube 5 (see Figs. 2 and 4) is mounted in the toppart of thecover and is held in place at its forward end by an inwardly turnedtiange 5a which engages a shoulder 6a of a belt feed tube lock 6, uponwhich it is mounted for oscillation as 7, and at its rear end by abearing 8 secured to the cover at 9, bearings 7 and 8 permittingoscillation of the tube 5 by the electrical charger and associated partsas subsequently to be described. The belt feed tube is provided with aplurality of peripheral longitudinal grooves lt), which act as gearteeth to engage a belt feed rack 11 forming a part of the feed assemblyfor automatically placing a live cartridge 12 into position to bechambered in response to rotation of the feed tube. The details of thebelt feed assembly are not pertinent to an understanding of thisinvention, therefore they have notl been illustrated or described yindetail.

The electric charger yisassembled inside of the belt feed tube as seenin Figure l, and comprises a motor assembly 13, a motor mount andbearing assembly 14, friction drive and drive spring assembly 15, a leadscrew and nut assembly 16, drive bushing assembly 17, follower assembly18, and magnetic brake 19.

rl`he electric charger will now be described in detail in connectionwith Figures 2, 2g, 3, 4 and 5, and the circuit diagram of Figure 6.`The motor mount is provided with 2 bayonet vslots 20 that engage pins 21located in the rear of the cover, and a A'spring biased motor mountlocking plunger 22 adaptedto be'received in a hole 23 in the cover top.In assembling the charger in the cover, the motor mount is given aclockwise twist and slots engage pin 21, at the same time plunger 22snaps into place within hole 23, to securely hold the charger in thecover. The mount is also provided with a forward extending reducedcylindrical portion 24 and an axial bore 25 enlarging into a rearwardlydisposed counterbore 25a. Within bore 25 is 'received for rotation anelongated forwardly extending friction drive tube 26. The rearward endof drive tube 26 extends into couuterbore 25a and is provided at itsrear end with an outwardly directed ange 27. Also received incounterbore 245 is a friction drive ball thrust bearing 28 comprising outer race 29 engaging the side wall of counterbore 25a and inner race 3Qwhich engages a short cam sleeve 31 secured to drive tube 26, sleeve 31having an enlarged rear end 32 abutting flange 27 of tube 26 on one endand the rear face of inner race at its forward end. The usual rollerbearing 30a is received between the inner and outer races.. The enlargedend 32 of sleeve 31 is provided with a beveled rearV cam face 33 for thepurpose to be later described. A friction drive shaft 34 is freelyreceived in drive tube 2 6 and is provided with a'forwardly extendingreduced portion 35; Shaft portionV 35 forms with the inner wall of drivetube 26 an annular chamber 3,6 for a purpose to be later described.

The motor assembly 13 and magnetic brake 194` are fastened to the rearof the motor mount assembly as follows. A thin annular cylindricalspacing member 37 is disposed between the rear flat face ofthe motor.mount and the forward face ofthe` motor housing, with its outerperipheral surface engaging the rearA inner wall of the cover. Motormountings screws (not shown) extend through axially alined` holes in themotor and, mount to secure the two members together. Received within thespace encompassed byl spacer 37 is a fiat disc like cylindrical member38 secured to the front face of the motor housing, and provided withdiametrical opposed longitudinal bores 39 (one shown Fig. 2) forreceiving compression springs 40. Inwardly of bores 39, in member 3Srisformed an annular groove or recess 41 in which is disposed a winding 42,combining with member 38 to form a solenoid housing of the magneticbrake. The solenoid housing is centrallyr apertured at 43 to provide abore into which extends rotating shaft 44 of the motor. Springs 4t) inbores 39 are connected at one end 45 to the motor housing and the otherend 46 to a disc-shaped substantially fiat armature 47 having annularface 48 which cooperates with an adjacent flat face 49 of the solenoidhousing. Springs 40 normally bias armature 47 out of engagement withsolenoid 38 when the solenoid winding 42 is deenergized, such that theadjacent faces are separated by an air gap of approximately .005. As canbe seen in Figures l', 2 and 6, this air gap is readily achieved withthe parts assembled as described above without the need for linemachining, adjustments or shimming of the associated parts. Additionallythis arrangement results in a relatively high pull for a brake of thissize. Friction drive shaft 34 is provided with a splined axial bore 34aat its rear end which makes a splined connection as at 48a with splinedmotor shaft 4d to conjointly rotate therewith when the motor fields areenergized. A short sleeve 49a is iixedly secured to the outer peripheryof the rear end of friction drive shaft 34, and ametallic brake disc 50is keyed to sleeve 49a to rotate with the friction drive shaft withincounterbore 25a. Nhen the brake solenoid 38 is deenergized to causesprings 4i) to press varmature t7 out of engagement therewith, armature47 is in position to frictionally engage the rear face of brake disc Silto thereby hold the motor against rotation.

Reduced forward portion 35 of friction drive shaft 34 loosely tits intohole 51 in the rear end of a forwardly extending elongated lead screw 52which has a smaller diameter than friction drive shaft 34 so that anannular chamber 53 is formed between the lead screw and drive'tube 26which is larger than chamber 36, between the drive tube and drive shaft,and substantially alined therewith. The'drive shaft is coupled to thedrive tube and to the lead screw by an elongated clutch spring 54 whichsurroundsthe drive shaft and lead screw and is constructed 'so as totightly grip the outer surface of the drive shaft for that'portion ofspring S4 disposed in annular chamber" 36, and to likewise tightly gripthe inner surface of drive tube for that portion of spring 54 disposed1n 'annular Vchamber 53. A rigid connection is provided between theylead screw and drive tube to insure that these twol elements rotate asa unit. This connection is formed by turning down the forward end ofdrive tube 26 to forni a flange 55. A block 56 is press tted in drivetube 26 to abut the iange 55, and is provided IwithV an axial hole 57 toscrew threadedly receive the lead screw 52. A pin 53 extendstransversely through block 56, lead screw S2 and drive tube 26 to securethese members together. It can readily be seen therefore that as themotor rotates drive shaft 34,- clutch spring 54 rotates drive tube l26and lead screw S2. Lead screw 52 extends forwardly substantially to theforward end of the cover, and is reduced at its forward end to form ajournal 59 which is received for rotation in a bearing 641- formed inbelt feed tube lock 6.

' The rotation of lead screw 52 lis instrumental in forcing rearwardlythe Adrive bushing assembly 17 for withdrawing the bolt, through themedium of the follower'assembly 1S. The follower assembly is mounted inthe lead screw and is located within a motor mount and followerguidesleeve 61 which is secured at its rear end to reduced portion 24 ofthe motor mount, 'and at its forward end in al recess 62 in followerstop 63 which is secured in any convenient manner about the lead screw ashort distance rearward of the forward end of the screw. Forward offollower stop 63 is disposed a rubber washer 64, which is engaged by aflanged enlargement 65 of the lead screw forwardly of washer 64, as thelead screw moves rearwardly in a manner and for a purpose to besubsequently described.

The follower assembly per se comprises a follower cover 66 which isrearwardly of, and abuts follower stop 63 when the follower assembly is.in forward position. A follower housing 677 which is formed as anelongated cylindrical sleeve slidingly engaging the inner wall of motormount and follower guide sleeve 61, is fastened at its forward end tothe follower cover and at its rear end to a follower bushing. 63disposed about lead screw 52. A follower spring 69 isyreceived in thefollower housing and extends between bushing 68 at the rear end and afollower nut 70 at the forward end, and about lead screw 52. Followerspring 6,95 maintains follower nut 70 .in position against the followercover and reduces the shock of sudden stopping of the nutkwhen thefollower assembly is stopped. The follower nut is threaded to travelforwardly and rearwardly upon the threads of the lead screw totherebycause the follower assembly to also move in coordination therewith. rIhefollower -assembly is prevented from rotating `by horizontal projections71 formed integrally with the follower housing and cover (see Fig. 3)theprojections in turn riding in longitudinal slots 72 in the motor mountand follower guide sleeve 61.

The follower projections 71 engage the drive bushing assembly and p-ullit rearward as the lead screw S2 turns clockwise in follower nut 70. Thedrive bushing assembly comprises a drive spring sleeve 73 whichslidingly engages the inner wall of belt feed tube and which has itsforward end turned down to form a ange 74 which slides upon the motormount and follower guide sleeve 61. Drive spring 75 surrounds the motormount and follower guide sleeve with the forward end contained withinthe drive spring sleeve land abutting flange 74 thereof, The rear of thedrive spring abuts the motor mount at the forward reduced portion 24.The drive bushing assembly comprmses the drive spring when the drivebushing assembly is pulled rearward on the power stroke. The drivespring provides the power for -driving the drive bushing assemblyforward. A connection between the drive bushing assembly and bolt, aslater to be described, also moves the bolt forward. Within the motormount yand guide follower sleeve 61 and surrounding the lead screw islocated fa relief ball bearing 76, at a location just forward of thepoint where the lead screw is joined to the friction drive assembly. Thepurpose of this bearing is to prevent the follower assembly from jammingand sticking against the friction drive assembly when the lead screw hasrotated sufficiently to move the follower lassembly rearwardly. Bearing76 comprises a flanged cup 77 disposed about the lead screw and havingforwardly directed edge 78 engaging the periphery of the follower guidesleeve 61. Within cup 77 is located a forward race 79, rear race 80 androller beatings 81 therebetween.

As previously explained the drive bushing assembly slides inthe beltfeed tube. A stud 82 projects downward from the drive bushing andengages a socket 83 in the top of the bolt. A roller 84 on the studrides in a track (not,V shown) formed by the sides of the cover toprevent the drive bushing assembly from turning in the cover. The stud82 is provided with hardened cam surfaces 82a which contact spiral slot84a (see Fig. 4) in the belt feed tube so that as the bolt moves forwardthe cam surface causes the belt feed tube to rotate about one half turnand to cause the belt feed gear teeth to move the belt feed rackll'toward the side ofthe gun -into which ammunition is being fed. As thebolt assembly and drive assembly move rearward the belt feed tuberotates in the opposite direction and moves the feed rack inwardly topull a cartridge to the center of the cartridge belt feed preparatory tochambering it. A sear assembly 200 is mounted in the bottom of thereceiver and normally held upward by a sear spring 201. As the boltmoves rearwardly the searr engages a shoulder 202 on the bottom of thebolt and holds it in rearward position until the Sear is depressed.

The remaining parts in the receiver of the machine gun which cooperatewith the electric charger and with the loading and firing circuit willnow be described. Buffer housing 35 located at the rear of the receiverhouses the buffer group (not shown in detail) for cushioning the recoilof the bolt assembly. A solenoid 86 fastened to the rear of the bufferhousing, comprises (see Fig. 6) coil assembly 87, armature 88, solenoidarm 89 which is pivotally connected to armature 88, as at 90 andsolenoid shield plate 91. Above the front end ofthe buffer housing islocated a firing circuit closer switch 92 comprising a switch arm 93pivotally connected as at 94 to a lower shoe 95. Lower shoe 95 and uppershoe 96 have a common pivotal connection 97 with the receiver, anddisposed between adjacent faces of shoes 95 and 96 is a compressionspring 98. As cam sleeve 31 and drive tube 26 are pushed rearwardlyunder the action of the lead screw, cam face 33 abuts upper shoe 96 andforces it to pivot counterclockwise against the action of spring 9S todepress lower shoe and move switch arm 93 out of engagement withcontacts in the return circuit and into engagement with contacts in thefiring circuit. (See Fig. 6*). The electrical charger is provided withcontacts 99 which mate will corresponding contacts 100 on the' rear endof the buffer housing when the cover is closed.

Referring to Figure 6 the power circuit for the magnetic brake andcharger motor, comprises source of power 101, connection to ground 102,and loading switch 103. From switch 103 the power circuit is connectedby way of conduit 104 to a tell tale switch arm 105, and to powercircuit Contact 106, via conduit 107 to the clockwise or power strokeeld 108 of the charger motor, then Via conduit 109, through armature 110and by way of conduit 111 to one side of the magnetic brake coil 42 andthen to ground.

The return circuit is traceable from loading switch 103 and tell taleswitch arm 105 to return circuit contact 113, then through conduit 114through upper contacts 115 of firing circuit closer switch 92, andthrough conduit 116 to counterclockwise or return stroke field 117 ofthe charger motor. From field 117 a conduit 118 connects with armature110, wherefrom conduit 111 connects to brake coil 42 and then to ground.

The firing circuit is traceable from power source 101 through conduit119 to lower contacts 120 of switch 92 which are engaged when shoes 95and 96 depress switch arm 93, through conduit 121 to firing switch 122and through the scar operating solenoid eld and then to ground.

As plainly seen in Figure linked to Sear arm 105a, has a forward flatsurface lying adjacent to and disposed behind a tell tale arm 122:1.Sear arm 105:1 is forwardly stepped to form a first thicker portion105b, and a second portion v105e thicker than portion 105b. Tell talearm 122a is notched as at 1221; and thickened portions 105b and 105eextend thro-ugh notch 12217 so that the shoulder formed by thickenedportion 1051 abuts the rear end of notch 12217 whereas the thickenedportion 105C abuts the sear 200, which is pivotally connected to thereceiver body and which is biased upwardly by a Sear spring 200:1.Rearwardly of the sear is also pivotally mounted a tell tale 124 whichhas a pin 124a extending horizontally therefrom to be received normallyin the forward end of an 6 solenoid arm 89 is pivotally arcuate slot 127in sear arm 105e. The tell tale has a.v

fixed connection with tell tale arm 122a so that as the tell tale isdepressed by the rearward travel of the bolt tell tale arm 122e alsomoves rearwardly and takes with it a switch cam arm 125 which has a rearend joined to the tell tale arm and a forward end joined to switch arm105,

such that depressing the tell tale breaks contact between switch arm 105and contact 106 and makes connection between switch arm 105 and contact113. Sear arm 105a is normally biased in a forward position by a springwhich is connected at one end to the sear arm and at the other end tothe tell tale arm. When the sear operating solenoid is energized Seararm 105a is drawn rearwardly so that thickened portion 105C abuts anddepresses sear 200 to release the bolt.

The operation of the electric charger and magnetic brake for a reloadingcycle will now be described. Just prior to reloading, the bolt head islocked in the breech ring assembly. Details of the bolt and breech ringassemblies form no part of the present invention and have not beendescribed in detail, however it suices to say' that buttress lockinglugs on the breech ring assembly engage with mating lugs on the outersurface of the bolt head to lock the bolt head in forward position. Thebolt head is swivelly mounted and may be turned for unlocking either byunlocking cam means which operates in conjunction with the recoil of thebarrel, or by cam lugs on the sides of the shank of the bolt operativein which extends forwardly andl spiral grooves in the bolt headassembly. The latter cam means is operable in response to a pull orbackward movement of the bolt assembly. A cartridge belt is placed inposition on the belt feed rack. Firing switch 122 is kept open, the searoperating solenoid remains deenergized, the sear and tell tale are intheir upward position, and switch arm 165 of the tell tale switch isengagement with contact 106. Loading switch 103 is now closed andcurrent proceeds fro-m power source 101 through switch 163, conduit iM,contacts MP and 106, conduit 107 to energize power stroke iield ill totend to turn the charger motor in a clockwise direction. Simultaneouslyfield 42 of magnetic brake 15, which is connected in series with thecharger' motor elds, is also energized to attract armature 47 whichmoves rearwardly against the bias of spring 4h to disengage brake disc5t). The charger motor is now free to turn clockwise, simultaneouslyturning friction drive shaft 34, and also lead screw 5.?. due to theaction of clutch spring 54 and associated parts. Rotation of lead screw52 causes follower nut 7b and the entire follower assembly to traversethe screw in a rearward direction, whereupon the drive bushing assemblyis engaged and also is moved rearwardly to compress drive spring 75.Thus the bolt will also be pulled rearwardly by virtue of its connectionwith the drive bushing assembly, the action serving to turn the bolthead so it will unlock from the breech ring assembly. As the bolttravels rearwardly, drive bushing roller S4 contacts the edge of spiralslot Sdu in the belt feed tube to rotate the tube and to force the beltfeed rack inward to thereby pull a cartridge toward the center of thecartridge belt feed way. In traveling rearward, the bolt is engaged bysear 200, and almost simultaneously engages and depresses tell tale 124which in turn moves tell tale arm 122:1 and tell tale cam arm 125rearwardly. The bolt remains locked in a rearward position by the sear.The tale switch arm 105 also moves rearwardly to open the power strokecircuit. At the same moment, because of the series connection betweenthe charger motor fields and the magnetic brake, and due to themechanical arrangement of brake and brake disc which provides for asmall air gap, the brake is instantly applied, i. e., springs ill forcearmature 47 into engagement with brake disc Sii to immediately stoprotation of the motor shaft and rotating charger parts. Tell tale switcharm then engages contact 113 to energize the return circuit. Thiscircuit is traceable from the tell tale switch through conduit 114,contacts 115 of switch 92, conduit 116 and return stroke field 117 andarmature 110 of the charger motor to tend to turn the motor incounterclockwise direction. Since magnetic bra-ke 4l) is also seriesconnected with the return stroke field of the motor, the brake is againenergized to attract armature 47 which disengages brake disc 50 topermit counterclockwise rotation of the charger parts. `The lead screwnow also turns counterclockwise through the action of the clutch spring,and the follower nut and follower parts now travel forwardly on the leadscrew, however the drive bushing assembly and bolt remains locked inrearward position due to the fact that the sear abuts shoulder 202 ofthe bolt. The follower nut and follower cease moving forwardly when thenut encounters follower stop 63, however the lead screw keeps turningand is therefore forced rearwardly. This rearward movement is alsotransmitted to friction drive tube 26 and cam sleeve 31 causing beveledrear cam face 33 to engage upper shoe 96 of switch 92. The upper shoepivots counterclockwise against spring 98 forcing lower shoe 95 andswitch arm 93 downward until the lower contacts of switch 92 in thetiring circuit are engaged. Connections are now made to enable thefiring of the gun and in tiring, loading switch 163 is opened and thetrigger is actuated. Since the trigger is Connected to firing switch122, by pressing the trigger this switch is closed and the searoperating solenoid is energized to depress the sear and tell tale,thereby energizing the firing circuit by Way of conduit 119, switch 92to the sear operating solenoid. Th trigger may be pressed as long asdesired for long or short bursts, and the bolt is now free to move backand forth actuated by the drive spring and usual recoil and countercoilmechanism. It is apparent that the charger motor is inoperative whilethe gun is tiring since contacts of switch 92 in the return strokefield, and loading switch 103 are open.

It can readily be seen that the provision of a magnetic broke insurespositive and immediate stopping of the charger motor and therebyprevents over-running. The positive brake action has been found to beextremely effective to dissipate armature energy and to prevent excessforces from being transmitted to the lead screw and to the motorcomponents.

Numerous other modifications and alterations of the structure which hasbeen disclosed herein for purposes of illustration will be apparent toone skilled in the art and it is obvious that the same may be madewithout departing from the spirit and scope of the invention as definedin the following claims.

I claim:

l. ln combination with a machine gun having a reciprocatory boltnormally adapted to be retracted by recoil forces of a tired cartridgefor automatically reloading the gun chamber, auxiliary mechanism forelectrically charging the gun comprising, a reversible electric motorhaving selectively energizable field coils in series therewith andhaving a rotating shaft, a forwardly extending drive shaft having asplined connection with said motor shaft, a lead screw having a frictiondrive connection with said drive shaft and with a cylindrical frictiondrive tube concentric with said drive shaft, said friction drive tubehaving an enlarged portion on its rear end having a forwardly beveledrear cam face, a drive bushing forwardly mounted on said lead screwadapted to rearwardly traverse said lead screw, follower means on saidlead screw forward of said drive bushing adapted to engage and to movesaid drive bushing rearwardly in response to clockwise rotation of saidlead screw, a stud protruding downwardly from said drive bushing andreceived in a socket in said bolt, a magnetic brake located forwardly ofsaid motor having a field winding connected.

in series with each of said motor fields, a brake disc mounted forrotation on said motor shaft, resilient means biasing said brake inengagement with said brake disc when said brake is deenergized, circuitmeans for selectively energizing each of said motor field coils, iirstnormal open switch means in said circuit closable to energize oney ofsaid eld coils to rotate said motor and lead screw clockwise and tosimultaneously energize said brake to release said motor and said leadscrew for clockwise rotation, said clockwise rotation of said lead screwcausing rearward travel of said drive bushing to move said bolt frombattery position to counterrecoil position, second switch means in saidcircuit cooperating with said bolt locking means and movable from firstposition, to deenergize said clockwise field and said brake to haltrotation of said motor and lead screw, to second position energizingsaid other tield in said motor and said brake to rotate said motor andlead screw in counterclockwise position, third switch means adapted tobe engaged by said friction drive tube camface upon continuedcounterclockwise rotation of said lead screw to deenergize said brakeand second counterclockwise field to halt rotation, and normally openfiring switch in said circuit elosable to release said bolt to lire saidgun.

2. ln combination with a machine gun, an electrically operated chargingand reloading mechanism comprising a housing, a motor in said housing, alead screw having a driving connection with said motor, a reciprocatorybolt for said gun, a cartridge belt feedway, means connecting said leadlscrew with said bolt, means connecting saidk lead screw with said beltfeedway adapted to place a cartridge from said feedway into loadingposition in response to rearward movement of said bolt, an electricpower source, means to connect said motor with said power source torotate said lead screw in one direction to retract said bolt frombattery position to counterrecoil position, means to lock said bolt incounterrecoil position, switch means interposed between said powersource and said motor simultaneously operable with said bolt lockingmeans to brake rotation of said motor and to rotate said motor and leadscrew in opposite direction, and second switch means actuable oncontinued rotation of said lead screw in said opposite direction adaptedto brake rotation of said motor and lead screw to enable pressure on thetrigger of said gun to `release said bolt to lire said gun, Vsaid meansto brake rotation of said gun comprising a flat, annular solenoidhousing including a field winding concentric with said motor drivingconnection and tixedly secured to the forward face of said motorhousing, a brake disc keyed to said motor driving connection forrotation therewith, a disc-shaped armature interposed between saidsolenoid housing and said brake disc, resilient means securing saidarmature to the forward face of said motor housing and normally biasingsaid armature into` engagement with said brake disc when said fieldwinding is deenergized.

3. In combination with a machine gun, an electrically operated chargingand reloading mechanism comprising a cup-shaped housing, a reversiblemotor in said housing and a motor shaft extending through the forwardface of said housing, a magnetic brake having a winding connected inseries with said motor, comprising a centrallyapertured disc-shapedmember secured to the forward face of said housing and concentric aboutsaid motor shaft, there being an annular recess in the forward face ofsaid disc-shaped member for receiving said winding, a lead screw havinga splined connection with the shaft of said motor, a brake disc mountedon said lead screw for rotation therewith and with said motor, adisc-shaped armature interposed between said disc-shaped member and saidbrake disc, resilient means normally biasing said armature intoengagement with said brake disc, a reciprocatory bolt for said gun, acartridge belt feedway, means connecting said lead screw with said bolt,means connecting said lead screw with said belt feedway adapted to placea first cartridge from a cartridge belt on said feedway into chargedposition when said bolt is moved rearwardly, an electric power sourcefor energizing said winding to thereby withdraw said armature againstthe bias of said resilient means to release said brake and rotate saidmotor in one direction to retract said bolt from battery position tocounterrecoil position, means to lock said bolt in retracted position,switch means interposed between said power source and said motorsimultaneously operable with said bolt locking means to halt thedirection of rotation of said motor and lead screw and to reverserotation of said motor and lead screw, and second switch means actuableon continued rotation of said motor and lead screw in said reversedirection adapted to deenergize said winding to brake rotation of saidmotor and said lead screw and to enable pressure on the trigger of saidgun to release said bolt to fire said un. g 4. In combination with amachine gun having a reciprocatory bolt normally adapted -to beretracted by recoil forces of a tired cartridge for automaticallyreloading the gun chamber, auxiliary mecahnism for electrically chargingthe gun comprising, a cup-shaped cylindrical housing, a reversibleelectric motor received in said housing and having selectivelyenergizable field coils -in series therewith and a rotating shaftextending through a forward face in said housing, a forwardly extendingdrive shaft having a splined connection with said motor shaft, a leadscrew having a friction drive connection with said drive shaft and witha cylindrical friction drive tube concentric with said drive shaft, saidfriction drive tube having an enlarged portion on its rear end providinga forwardly beveled rear cam face, a drive bushing forwardly mounted onsaid lead screw adapted to rearwardly traverse said lead screw, followermeans on said lead screw forward of said drive bushing adapted to engageand to move said drive bushing rearwardly in response to clockwiserotation of said lead screw, a stud protruding downwardly from saiddrive bushing and received in a socket in said bolt, a magnetic brakehaving a field winding connected in series with each of said motor eldsand comprising a centrally apertured disc-shaped member secured to theforward face of said motor housing and concentric about said motorshaft, there being an annular recess formed in the forward face of saiddiscshaped member to provide a housing for said field winding, a brakedisc keyed to rotate with said motor shaft and spaced axially forwardlyof said disc-shaped member, a disc-shaped armature interposed betweensaid discshaped member and said brake disc, resilient means secur` ingsaid armature to the forward face of said motor housing and urging saidarmature into engagement with said brake disc when said field winding isdeenergized, circuit means for selectively energizing each of said motorfield coils, first normally open switch means in said circuit closableto energize one of said field coils to rotate said motor and lead screwin a clockwise direction and to simultaneously energize said eld winding'to release said motor and said lead screw for clockwise rotation, Isaidclockwise rotation of said lead screw causing rearward travel of saiddrive bushing to move siad bolt from battery position to counterrecoilposition, second switch means in said circuit cooperating with said boltlocking means and movable from first position, to deenergize saidclockwise field and said field winding to halt rotation of said motorand lead screw, to second position energizing said other eld in saidmotor and said field winding to rotate said motor and lead screw incounterclockwise position, third switch means adapted to be engaged bysaid friction drive tube cam face upon continued counterclockwiserotation of said lead screw to deenergize said field winding and secondcounterclockwise field to halt rotation, and normally open tiring switch-in said circuit closeable to release said bolt to tire said gun.

5. In combination with a machine gun having a reciprocatory boltnormally adapted to be retracted by' recoil forces of a fired cartridgefor automatically reload ing the gun chamber, auxiliary mechanism forelectrically charging said gun and comprising an elongated cylindricalbelt fed ltube mounted for oscillation adjacent said gun and along thepath of movement of said bolt, there being a spiral slot in said beltfeed tube engageable by said reciprocatory bolt to oscillate said beltfeed tube, a cartridge belt feedway mounted laterally of said belt feedtube, means on said tube providing a driving connection between saidtube and said belt feedway for moving a cartridge into position intosaid gun chamber in response to retraction of said bolt, a reversiblemotor mounted adjacent the rear end of said belt feed tube and having aforwardly extending drive shaft extending concentrically within saidbelt feed tube, a lead screw concentric within said belt feed tube andextending forwardly of said drive shaft, means providing a driveconnection between said drive shaft and said lead screw, a traversingnut mounted on said lead screw, a drive bushing mounted on said leadscrew adapted to be engaged by said traversing nut for rearward movementin response to clockwise rotation of said lead screw, means providing afixed connection between said bolt and said drive bushing, a drivespring concentric about said drive shaft normally biasing said drivebushing forwardly against said traversing nut, said motor having a powerfield energizable -to rotate said lead screw clockwise and a return ieldfor rotating said lead screw counterclockwise, a magnetic brake mountedrearwardly of said motor and having means resiliently biased to normallyengage said 11 drive `shaft and `to lock said shaft against rotation, abrake winding in said brake Connected in `series with said power andreturn elds energizable to release said brake to permit rotation of saiddrive shaft, circuit means for selectively energizing each of said motorfield coils, rst normally open switch means in said circuit closable tosimultaneously Venergize said brake winding to disengage said driveshaft and to permit clockwise rotation of said lead screw to therebymove said bolt from battery to counterrecoil position, means in said gunadjacent the rear end of said belt feed tube for locking said bolt incounterrecoil position, a selector switch in said circuit cooperatingwith said bolt locking means selectively movable from first position todeenergize said clockwise field and said brake winding to halt clockwiserotation, to second position energizing said return eld and said brakewinding to permit counterclockwise rotation of said eld and 4to returnsaid traversing nut to the forward end of said lead screw, a thirdswitch in said circuit closable upon continued counterclockwise rotationof said lead screw to deenergize said brake winding and said kreturnfield, and a normally-open tiring switch closable to withdraw said boltlocking means, whereby said bolt is released -to re said gun.

References Cited in the le of this patent UNITED STATES PATENTS1,961,349 Gordon June 5, 1934 2,180,751 Wagner Nov. 2l, 1939 2,413,241Mejean et al. Dec. 24, 1946 2,413,416 Astlund et al. Dec. 3l, 19462,472,002 Clark May 3l, 1949 FOREIGN PATENTS 914,885 France July 1, 1946

